I don't agree. I could process several medium complicated test cases I
have collected over the time with pdfetex 1.30.5 from TL2005 (debian
packages) with my context packages for 2007.01.12.
The only point was that is was necessary to add the pdfetex -> pdftex
symlink, otherwise everything worked without problem.
So I *don't see that this was an *absolute* move.

Of course you could add a set of font synonyms to cont-usr.tex
or even create symlinks like from cmsy10.tfm to lmsy10.tfm. But
you know that no 'ordinary' user will know what to do, and such
hacks are probably a bad idea for such users anyway, because it
will come back to haunt them next year or the year after.

This is at least in part why TL will run 2007.01.12, and I will no
update it any more, as well as why we have a fullblown repository
of old releases.

At this point, I will not touch TL any more, except for urgent
bugfixes. Staszek added the new latin modern at the very last
moment, and I do not want to risk having a completely bodged
system on TeXLive like we have had in some previous years.
In fact, I still cannot quite believe that this release is going
to work out ok.
Perhaps Hans can be convinced to add a backward-compatibily switch
for the normal context releases (>2007.01.23), but that is not
upto me.
Best wishes,
Taco